Tom Cruise and Dustin Hoffman, who starred in the film of Rain Man are undoubtedly a tough act to follow.

But Oliver Chris and Neil Morrissey bring this modern morality tale vividly to life.

The story concerns Charlie Babbitt (Chris) an avaricious wheeler dealer who has creditors snapping at his heels, when his estranged father dies, leaving $12m.

But not to Charlie, who gets only the vintage car, which was the cause of his falling out with the late Charles Babbitt senior.

Aggrieved son sets out to discover who is the unnamed beneficiary and finds he has an elder brother Raymond, an autistic savant, who has been living in a home for most of Charlie’s life.

When Charlie basically kidnaps Raymond with the intention of recovering at least half of the $12m for himself, Raymond is able to fill in details of their early life and selfish Charlie begins to change.

Morrissey is profoundly convincing as the autistic man, expressionless, unless seriously disturbed by the lack of routine which Charlie’s life on the run presents to him.

And then he chants old film or television comedy routines at high speed, without a hint of irony or humour.

He rattles off complex mathematical calculations – which gives Charlie a big break when he gets Raymond to Los Angeles and the casinos.

Chris handles the gradual changes in Charlie’s attitude meticulously. It’s not a road to Damascus conversion – the guy is still a rogue – but he is moved by the brother who cannot respond emotionally and the ending had most people surreptitiously fishing for the tissues.

The sets are economical and the construction allows quick scene changes which maintain a sharp pace.

It is funny and moving.

You’ll be sorry if you miss it. Rain Man is at Bath until Saturday.